Machine drive



Dec. 3l, 1929. 1 P GRABER 741,695

MACHINE DRlvE Filed Aug. 4, 1927 Patented Dec. 31, 1929 JONATHAN P. GRABER, OF BLOOMFIELD, MONTANA MACHINE DRIVE Application filed August 4, 1937. Serial No. 2107676.

The object ott the invention is to provide a mechanism adapted tor application to machines the operation of which require rotary motion and in wl ich the driving means is oscillatory or reciprocatory, as when a treadle is used; to provide a construction of this character in which a driving` force is imparted during both strokes or' the reciproci.- tory or oscillatory member; to provide a construction in which the condition commonly known as a dead center is effectively avoided; and to provide a construction in which eiiective braking action is had when the reciprocatory member is retained or held at either extremity of its stroke.

With this object in view, the invefition consists in a construction and combination oi parts oi which a 'preferred embodiment is illustrated in the accompanying drawings7 wherein Figure l is a side elevational view showing the application of the invention as a driving means for a sewing machine, such parts of the latter as are necessary only to a full understanding of the invention being shown.

Figure 2 is a sectional view on the plane indicated by the line 2-2 ot Figure l.

Figure 3 is a detail sectional view on the plane indicated by the line 3d?, ot Figure 2. Figure i is a detail sectional View on the plane indicated by the line 4Cl ot Figure l.

ln the illustrated embodiment of the invention the drive wheel l0 which is of the conventional form used in sewing machines is peripherally greoved tor the reception of the belt l1 by means el' which the machine is driven. rEhe drive wheel is rotatably mounted on the iiXed or stationary shaft l2, the latter being secured in the frame 14 of the machine by means or' a nut l5 which engages the threaded extremity' of the shaft and abuts the outer face of the trame, the shaft being shouldered as indicated at 16 to provide an inner abutment so that rigid connection with the trame may be secured. Ball bearings i7 and 18 provide for the free running or' the drive wheel7 the latter being retained by a cone i9 carried on the threaded portion 2O of the sha'tt l2. Cones 2l and 22 are mounted on the threaded portion, being threadingly engaged with the latter and the Jformer is seated against a washer 23 interposed between it and the cone 19. rlhe latter cone, when properly positioned is retained at the proper settingby means ot a lock nut 24. rlhe cones 2l and 22 support the ball bearings 25 and 2b, the latter `providing ttor the tree swinging movement oit the arms 27 between which is interposed a ball thrust bearing 2S.

The armsertend radially from the shaft l2 and lie within the rim portion 29 or the drive wheel. Pivotally mounted at the extremities oli the arms are bell-crank levers 80, these levers being carried on screw studs 3l threadingly engaged with the arms. rThe shorter arms oi the bell-crank levers are of arcuate shape being formed to substantially the same rad'us as the inner peripheral surface oit the rim 29 and on their outer' faces are provided with friction plates 32. Booked in one direction on their pivot studs 3l, the friction faces 32 engage the inner periphery of the rim 29. B cked in the other direction, they are released from such engagement. The levers 8O extend radially inward and adjacent the shaft are provided with screw studs 33 with which the extremities of the pitmen are pivotally connected. 'E he two pitmen are pivotally connected. together at the remote ends as indicated at 35 and one of them has a rpivotal connection 36 with a treadle 37.

The arms 27 are provided with integral ears 38 overhangingv the longer arms of the levers 430 and threadingly engagedv in these ears are the sleeves 39 which are adjustable ears by reason of the threads. the desired adjustment being maintained by means of lool; nuts l() threadingly engaged with the sleeves and abutting the ears. Compression springs 4l are housed in the sleeves the outer ends of which are interiorly threaded for the reception of blind adjusting screws 4t2, the latter bearing upon the ends oi' the springs of which' the opposite ends bear on the edges ot the longer varms of the levers 30.

One of vthe pitmen 3a is provided with a cushion 43 serving as a spacer between it and the other pitinan when the two are brought close together as at the extremities oit the strokes of the treadle 37.

A dust cap le encloses the lock nut 24, the of said levers, and cushioning means carried core 22 and ball bearing 26, being` retained in by the arms and yieldingly impelling the position by a screw l5 threadingly engaged levers in one direction. with a tapped hole in the extremity of the In testimony whereof he al'iixes his signathreaded portion 2O of the shaft l2.

In the operation of the invention, the depression of the treadle will exert perforce a pull on both pitmen and thus tend to rock the bell-crank levers on their pivotal connec tions on the arms 27. levers are on opposite sides of the axis of the wheel, however, the friction foot of one will be brought into irm frictional engagement with the inner periphery of the rim 29 but the other will be rocked away from such engagement. Therefore on the down strolre of the treadle one of the levers operates as a means for communicating motion to the wheel. On the release or upward movement of the treadle the previously engaged lever will be released and the other thrown into engagement with the inner peripheral surface of the rim. Thus both strokes of the treadle serve to communicate rotary motion to the drive wheel and by reason of the fact that the spacer 43 prevents the pitmen from coming together at their upper ends the pivotal connection of neither with its respective lever 30 will at any time fall in a line passing through the axis of the drive wheel and the pivotal connection of the pitman with the treadle. Therefore there can be no such condition as a dead center and irrespective of the positionA of the drive wheel, the latter may always be started initially by pressure upon the treadle. Also the construction provides for a braking action in that continued pressure on the treadle at the end of its stroke will apply a force tending to rock one of the levers 30 and thus bring its friction foot into binding engagement with the inner periphery of the rim 29, thus resisting movement of the wheel as long as pressure is maintained on the treadle.

The springs 41 serve as a means for impellingr the levers in a direction to force the friction feet into engagement with the rim and thus provide against lost motion and rattling while retaining the levers in their most effective pickup position for gripping action on the rim.

The invention having been described, what is claimed as new and useful is:

A machine drive comprising a drive wheel provided with a rim, arms pivotally mounted for swinging movement about the aXis of the drive wheel, bell-crank levers piv- -otally mounted at the outer extremities of said arms, the shorter arms of said levers being adapted for gripping action on said wheel rim and the longer arms terminating adjacent the axis of the drive wheel, a reciprocatory member, pitmen pivot-ally connected at one end with the reciprocatory member and at the remote ends with the inner extremities Since the bell-crank ture.

JONATHAN P. GRABER. 

